Issues with support generation

[bearsbeets 0]

I have a part with threading on the bottom and features above features that need support. I have found the only way to get any support for those parts on the top is by enabling support placement "everywhere." However, when I do this support is generated over the threads which I cannot seem to remove with support blockers. I cannot change support settings to be too far from the object otherwise the nylon I am printing with will droop dramatically. I have also tried increasing X/Y distance to make the supports less of an issue with the threads, but I can't make it far enough that it won't interfere with the threads, but will still support the print where it's needed. When print everywhere is enabled, the support walls hug the threads regardless of what settings I change.

I have had this issue on other parts as well where print supports "everywhere" would negatively impact the print quality but had no other option due to an overlap that required support.

 

Any help is appreciated,

Thank you!

Slick Upper.stl

[GregValiant 1,251]

This is with a rectangular support blocker covering the threads.

Within my gray circled area the threads are being supported as evidenced by the support interface roof lines.  I  played with the settings and I could not eliminate this.  The results were the same with a 34mm diameter x 12 cylinder and with a 34mm diameter x 195 cylinder.  Switching from Tree to Normal supports made no difference, the threads were still being supported.  Even with the support angle at 75° the threads were being supported and that should have been beyond the (I assume) 60° included angle of the thread form.

 

I've worked with models with similar features but I've never seen this problem.   What Cad software was used to design this and how was the STL file generated?  (There were a couple minor problems with the model but a repaired STL sliced exactly the same.)

 

Maybe @Torgeir, @geert_2, @nallath, @gr5 or one of the other more experienced people have a better take on what's going on.  I hate being baffled before my second cup of coffee.

 

 

I'm still baffled.  This is with a support blocker covering the entire model.

 

 

Here is the top layer.  The support is not supporting anything, and the threads are still supported.

 

So I went back to the "repaired" model and tried again.  I had been playing with the support settings for the un-repaired model when I brought the fixed model in.  This time I went back to my defaults before bringing the fixed model in.  I think it worked.

I have now set a personal record for most attachments to a post.

 

 

 

SlickUpper_fixed.3mf

Edited August 4, 2021 by GregValiant

[geert_2 557]

Up till now I have only printed single-nozzle models, thus with support in the same material as the part, and with older Cura-versions. So I can't really say what is going on here, or what the best option is.

 

If I had to print it for myself, and if the model and function would allow it, I would redesign it slightly, so it can be printed without supports. By adding 45° angles to the overhanging areas. And I would use a brim (or even custom designed brim) to keep it stable on the bed, to prevent it from being knocked over.

 

If redesigning would not be possible due to its functionality, I might consider designing custom supports, maybe a mix of free-hanging supports with an interface-layer of PVA? But I don't know if this would work, I never tried it. See the concepts below.

 

Concept of (almost) free-hanging supports:

 

As printed (the middle part of the bridge got similar almost free-hanging supports, but they are not shown in the CAD-model above):

 

After cleaning-up: there is very little damage to the side-walls due to the thin connection-strands, and of course no damage at all to the design at the bottom. For reference: all walls are 1mm thick here:

 

Concept sketch of basic support structure in PLA, with a dove-tail interface in PVA, so the bottom areas of the real model on top are kept clean. This would give a very stable support base, easy to print in cheap PLA (in case the model is PLA). The dove-tail is to have the support-interface in PVA stick very well to the PLA base. But as said: I don't know if this would work in reality, never tried it yet, but it seems like it should work.   :-)

 

If you would consider these concepts, do tests on small dedicated test-models, so you don't waste too much time and material. Stay with the printer and watch closely how it prints.

 

[bearsbeets 0]

On 8/14/2021 at 10:38 AM, geert_2 said:

Up till now I have only printed single-nozzle models, thus with support in the same material as the part, and with older Cura-versions. So I can't really say what is going on here, or what the best option is.

 

If I had to print it for myself, and if the model and function would allow it, I would redesign it slightly, so it can be printed without supports. By adding 45° angles to the overhanging areas. And I would use a brim (or even custom designed brim) to keep it stable on the bed, to prevent it from being knocked over.

 

If redesigning would not be possible due to its functionality, I might consider designing custom supports, maybe a mix of free-hanging supports with an interface-layer of PVA? But I don't know if this would work, I never tried it. See the concepts below.

 

Concept of (almost) free-hanging supports:

 

As printed (the middle part of the bridge got similar almost free-hanging supports, but they are not shown in the CAD-model above):

 

After cleaning-up: there is very little damage to the side-walls due to the thin connection-strands, and of course no damage at all to the design at the bottom. For reference: all walls are 1mm thick here:

 

Concept sketch of basic support structure in PLA, with a dove-tail interface in PVA, so the bottom areas of the real model on top are kept clean. This would give a very stable support base, easy to print in cheap PLA (in case the model is PLA). The dove-tail is to have the support-interface in PVA stick very well to the PLA base. But as said: I don't know if this would work in reality, never tried it yet, but it seems like it should work.   🙂

 

If you would consider these concepts, do tests on small dedicated test-models, so you don't waste too much time and material. Stay with the printer and watch closely how it prints.

 

It'd probably be easier for me to try and redesign the file than build a multi-fillament setup unfortunately.
If I get that sort of setup in the future. I will look into your suggestion. For multi-material supports, do you design the internal support structure as well or is that generated?

[bearsbeets 0]

On 8/4/2021 at 6:40 AM, GregValiant said:

This is with a rectangular support blocker covering the threads.

Within my gray circled area the threads are being supported as evidenced by the support interface roof lines.  I  played with the settings and I could not eliminate this.  The results were the same with a 34mm diameter x 12 cylinder and with a 34mm diameter x 195 cylinder.  Switching from Tree to Normal supports made no difference, the threads were still being supported.  Even with the support angle at 75° the threads were being supported and that should have been beyond the (I assume) 60° included angle of the thread form.

 

I've worked with models with similar features but I've never seen this problem.   What Cad software was used to design this and how was the STL file generated?  (There were a couple minor problems with the model but a repaired STL sliced exactly the same.)

 

Maybe @Torgeir, @geert_2, @nallath, @gr5 or one of the other more experienced people have a better take on what's going on.  I hate being baffled before my second cup of coffee.

 

 

I'm still baffled.  This is with a support blocker covering the entire model.

 

 

Here is the top layer.  The support is not supporting anything, and the threads are still supported.

 

So I went back to the "repaired" model and tried again.  I had been playing with the support settings for the un-repaired model when I brought the fixed model in.  This time I went back to my defaults before bringing the fixed model in.  I think it worked.

I have now set a personal record for most attachments to a post.

 

 

 

SlickUpper_fixed.3mf 450.32 kB · 1 download

 

On 8/4/2021 at 6:40 AM, GregValiant said:

This is with a rectangular support blocker covering the threads.

Within my gray circled area the threads are being supported as evidenced by the support interface roof lines.  I  played with the settings and I could not eliminate this.  The results were the same with a 34mm diameter x 12 cylinder and with a 34mm diameter x 195 cylinder.  Switching from Tree to Normal supports made no difference, the threads were still being supported.  Even with the support angle at 75° the threads were being supported and that should have been beyond the (I assume) 60° included angle of the thread form.

 

I've worked with models with similar features but I've never seen this problem.   What Cad software was used to design this and how was the STL file generated?  (There were a couple minor problems with the model but a repaired STL sliced exactly the same.)

 

Maybe @Torgeir, @geert_2, @nallath, @gr5 or one of the other more experienced people have a better take on what's going on.  I hate being baffled before my second cup of coffee.

 

 

I'm still baffled.  This is with a support blocker covering the entire model.

 

 

Here is the top layer.  The support is not supporting anything, and the threads are still supported.

 

So I went back to the "repaired" model and tried again.  I had been playing with the support settings for the un-repaired model when I brought the fixed model in.  This time I went back to my defaults before bringing the fixed model in.  I think it worked.

I have now set a personal record for most attachments to a post.

 

 

 

SlickUpper_fixed.3mf 450.32 kB · 1 download

"I've worked with models with similar features but I've never seen this problem.   What Cad software was used to design this and how was the STL file generated?  (There were a couple minor problems with the model but a repaired STL sliced exactly the same.)"

These are good questions lol. I could upload the STEP file as well. I do not have an answer to your two questions though.

In that last picture, are you saying that you were able to resolve the issue? What settings did you change?

[GregValiant 1,251]

Geez, I'm old ya know.  I can't remember what I had for breakfast this morning so going back to what I did a month ago ain't happenin'.

 

I think if you open that "SlickUpper_fixed.3mf" file in my previous post you will get the repaired model and whatever settings I had.  As I recall, the problem was at the top of the model (when vertical) and a non-manifold edge was fooling Cura into thinking the top of the cylinder was covered and that's what was causing all the support on the inside.